title: Inhibition and stimulation of respiration-linked Mg2+ efflux in rat heart mitochondria.
abstract: Respiration-driven Mg2+ efflux from rat heart mitochondria has been studied in different conditions. Almost total release of Mg2+ from the mitochondria occurs upon addition of a proton/bivalent cation exchanger, A23187. The content of Mg2+ remaining in mitochondria after A23187 treatment is the same if part of the mitochondrial Mg2+ has already been extruded through the energy-linked mechanism. Some inhibition of Mg2+ efflux is observed in the presence of high concentrations of La3+ (100 micro M). A proton/monovalent cation exchanger, nigericin, completely prevents Mg2+ efflux, whereas a cation conductor, valinomycin, considerably stimulates it. The results indicate that the main part of mitochondrial Mg2+ is present in the membrane-bounded compartment, probably in the matrix space. The driving force of the Mg2+ efflux appears to be the proton gradient (deltapH) created by mitochondrial respiration.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D009550:Nigericin / Q000494:pharmacology; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D014634:Valinomycin; D000001:Calcimycin; D007811:Lanthanum; D008274:Magnesium; D009550:Nigericin